pt::peg::to::container(n)

📦

version 2.0 · 2 versions

2.0 · fedora 43, fedora 44, nixos 26.05, nixpkgs unstable (latest)
1.21 · alpine 3.24, epel 9, opensuse-leap 16.0

, in fedora 43, fedora 44, nixos 26.05, nixpkgs unstable

💖 pt::peg::to::container — the `pt::peg::to::container(n)` page 💖

okay bestie, welcome to the Parser Tools zone — specifically the bit that turns parsing expression grammars into CONTAINER markup. Let's get into it 🦋

✨ NAME ✨

pt::peg::to::container — PEG Conversion. Write CONTAINER format. that's literally the whole vibe. 💅

🌸 SYNOPSIS 🌸

package require Tcl 8.5 9

package require pt::peg::to::container ?1.1?

package require pt::peg

package require text::write

package require char

pt::peg::to::container reset

pt::peg::to::container configure

pt::peg::to::container configure option

pt::peg::to::container configure option value...

pt::peg::to::container convert serial

look at all those commands, she's serving range 💅

🎀 DESCRIPTION 🎀

Are you lost ? Do you have trouble understanding this document ? 😭 bestie if that's you, pls go read the overview in the Introduction to Parser Tools. That doc is the entrypoint to the whole system this package is part of, fr fr. 🫶

This package implements the converter from parsing expression grammars to CONTAINER markup.

It resides in the Export section of the Core Layer of Parser Tools, and it can be used either directly with the other packages of this layer, or indirectly through the export manager provided by pt::peg::export. That indirect route is intended for use in untrusted environments, and it happens through the corresponding export plugin pt::peg::export::container, which sits between the converter and the export manager. a little middleman moment, we love a buffer 🧚

IMAGE: arch_core_eplugins — yes there's a diagram, go look at it, it's giving architecture 💖

⭐ API ⭐

The API provided by this package satisfies the specification of the Converter API found in the Parser Tools Export API specification. no cap, it's compliant. 👑

pt::peg::to::container reset — This command resets the configuration of the package to its default settings. factory reset but make it cute ✨
pt::peg::to::container configure — This command returns a dictionary containing the current configuration of the package. your settings, served on a lil platter 🍓
pt::peg::to::container configure option — This command returns the current value of the specified configuration option of the package. For the set of legal options, please read the section Options. iykyk 📖
pt::peg::to::container configure option value... — This command sets the given configuration options of the package, to the specified values. For the set of legal options, please read the section Options. glow-up time, bestie 💅
pt::peg::to::container convert serial — This command takes the canonical serialization of a parsing expression grammar, as specified in section PEG serialization format, and contained in serial, and generates CONTAINER markup encoding the grammar, per the current package configuration. The created string is then returned as the result of the command. main character energy: in goes a grammar, out comes markup ✨

💅 OPTIONS 💅

The converter to the CONTAINER format recognizes the following options and changes its behaviour as they specify. she's got range, she's got preferences, respect it.

-file string — The value of this option is the name of the file or other entity from which the grammar came, for which the command is run. The default value is unknown. mystery file origin, iconic 🙈
-name string — The value of this option is the name of the grammar we are processing. The default value is a_pe_grammar. she has a name and it's serving 🎀
-user string — The value of this option is the name of the user for which the command is run. The default value is unknown. anonymous era 💜
-mode bulk|incremental — The value of this option controls which methods of pt::peg::container instances are used to specify the grammar, i.e. preload it into the container. There are two legal values, as listed below. The default is bulk. pick your fighter ⚔️
- bulk — In this mode the methods start, add, modes, and rules are used to specify the grammar in a bulk manner, i.e. as a set of nonterminal symbols, and two dictionaries mapping from the symbols to their semantic modes and parsing expressions.

This mode is the default. drop it all at once, one big slay ✨

incremental — In this mode the methods start, add, mode, and rule are used to specify the grammar piecemal, with each nonterminal having its own block of defining commands. one nonterminal at a time, we're taking it slow 🦋

-template string — The value of this option is a string into which to put the generated code and the other configuration settings. The various locations for user-data are expected to be specified with the placeholders listed below. The default value is "@code@". a lil fill-in-the-blanks moment 📝
- @user@ — To be replaced with the value of the option -user.
- @format@ — To be replaced with the constant CONTAINER.
- @file@ — To be replaced with the value of the option -file.
- @name@ — To be replaced with the value of the option -name.
- @mode@ — To be replaced with the value of the option -mode.
- @code@ — To be replaced with the generated code. the moment we've all been waiting for ✨

🌈 GRAMMAR CONTAINER 🌈

The container format is another form of describing parsing expression grammars. While data in this format is executable it does not constitute a parser for the grammar. It always has to be used in conjunction with the package pt::peg::interp, a grammar interpreter. so it's executable but it's NOT a parser, do not get it twisted bestie 😭

The format represents grammars by a snit::type, i.e. class, whose instances are API-compatible to the instances of the pt::peg::container package, and which are preloaded with the grammar in question.

It has no direct formal specification beyond what was said above. vibes-based spec, honestly iconic 🧚

💖 EXAMPLE 💖

Assuming the following PEG for simple mathematical expressions

PEG calculator (Expression)
    Digit      <- '0'/'1'/'2'/'3'/'4'/'5'/'6'/'7'/'8'/'9'       ;
    Sign       <- '-' / '+'                                     ;
    Number     <- Sign? Digit+                                  ;
    Expression <- Term (AddOp Term)*                            ;
    MulOp      <- '*' / '/'                                     ;
    Term       <- Factor (MulOp Factor)*                        ;
    AddOp      <- '+'/'-'                                       ;
    Factor     <- '(' Expression ')' / Number                   ;
END;

one possible CONTAINER serialization for it is

snit::type a_pe_grammar {
    constructor {} {
        install myg using pt::peg::container ${selfns}::G
        $myg start {n Expression}
        $myg add   AddOp Digit Expression Factor MulOp Number Sign Term
        $myg modes {
            AddOp      value
            Digit      value
            Expression value
            Factor     value
            MulOp      value
            Number     value
            Sign       value
            Term       value
        }
        $myg rules {
            AddOp      {/ {t -} {t +}}
            Digit      {/ {t 0} {t 1} {t 2} {t 3} {t 4} {t 5} {t 6} {t 7} {t 8} {t 9}}
            Expression {/ {x {t \50} {n Expression} {t \51}} {x {n Factor} {* {x {n MulOp} {n Factor}}}}}
            Factor     {x {n Term} {* {x {n AddOp} {n Term}}}}
            MulOp      {/ {t *} {t /}}
            Number     {x {? {n Sign}} {+ {n Digit}}}
            Sign       {/ {t -} {t +}}
            Term       {n Number}
        }
        return
    }

    component myg
    delegate method * to myg
}

ate. no crumbs. 💅✨

🦋 PEG SERIALIZATION FORMAT 🦋

Okay so bestie, this is the part where we talk about the format. Like, the actual shape of the thing when Parser Tools flattens a Parsing Expression Grammar into an immutable value so it can travel around, get compared to other grammars, and generally live its best life. ✨

There are two flavours here: regular and canonical serializations. A PEG can have more than one regular serialization (messy, chaotic, a little unhinged 💅) but exactly one of them will be canonical. Canonical is the one true version, no cap.

🌸 regular serialization 🌸

The serialization of any PEG is a nested Tcl dictionary. Yes, dictionaries inside dictionaries. It's giving inception 🌀
This dictionary holds a single key, pt::grammar::peg, and its value. That value holds the contents of the grammar.
The contents of the grammar are a Tcl dictionary holding the set of nonterminal symbols and the starting expression. The relevant keys and their values are:
- rules — The value is a Tcl dictionary whose keys are the names of the nonterminal symbols known to the grammar.
  1. Each nonterminal symbol may occur only once. Once. That's it. No duplicates, periodt.
  2. The empty string is not a legal nonterminal symbol. (So don't even try it 🙈)
  3. The value for each symbol is a Tcl dictionary itself. The relevant keys and their values in this dictionary are:
    - is — The value is the serialization of the parsing expression describing the symbol's sentennial structure, as specified in the section PE serialization format.
    - mode — The value can be one of three values specifying how a parser should handle the semantic value produced by the symbol.
      - value — The semantic value of the nonterminal symbol is an abstract syntax tree consisting of a single node node for the nonterminal itself, which has the ASTs of the symbol's right hand side as its children.
      - leaf — The semantic value of the nonterminal symbol is an abstract syntax tree consisting of a single node node for the nonterminal, without any children. Any ASTs generated by the symbol's right hand side are discarded. 🗑️
      - void — The nonterminal has no semantic value. Any ASTs generated by the symbol's right hand side are discarded (as well).
- start — The value is the serialization of the start parsing expression of the grammar, as specified in the section PE serialization format.
The terminal symbols of the grammar are specified implicitly as the set of all terminal symbols used in the start expression and on the RHS of the grammar rules. (Implicitly!! She's mysterious like that 🎀)

👑 canonical serialization 👑

The canonical serialization of a grammar has the format as specified in the previous item, and then additionally satisfies the constraints below, which make it unique among all the possible serializations of this grammar.

The keys found in all the nested Tcl dictionaries are sorted in ascending dictionary order, as generated by Tcl's builtin command lsort -increasing -dict.
The string representation of the value is the canonical representation of a Tcl dictionary. I.e. it does not contain superfluous whitespace. ✨ Clean. Minimal. Iconic.

💖 EXAMPLE 💖

Assuming the following PEG for simple mathematical expressions:

PEG calculator (Expression)
    Digit      <- '0'/'1'/'2'/'3'/'4'/'5'/'6'/'7'/'8'/'9'       ;
    Sign       <- '-' / '+'                                     ;
    Number     <- Sign? Digit+                                  ;
    Expression <- Term (AddOp Term)*                            ;
    MulOp      <- '*' / '/'                                     ;
    Term       <- Factor (MulOp Factor)*                        ;
    AddOp      <- '+'/'-'                                       ;
    Factor     <- '(' Expression ')' / Number                   ;
END;

then its canonical serialization (except for whitespace) is:

pt::grammar::peg {
    rules {
        AddOp      {is {/ {t -} {t +}}                                                                mode value}
        Digit      {is {/ {t 0} {t 1} {t 2} {t 3} {t 4} {t 5} {t 6} {t 7} {t 8} {t 9}}                mode value}
        Expression {is {x {n Term} {* {x {n AddOp} {n Term}}}}                                        mode value}
        Factor     {is {/ {x {t (} {n Expression} {t )}} {n Number}}                                  mode value}
        MulOp      {is {/ {t *} {t /}}                                                                mode value}
        Number     {is {x {? {n Sign}} {+ {n Digit}}}                                                 mode value}
        Sign       {is {/ {t -} {t +}}                                                                mode value}
        Term       {is {x {n Factor} {* {x {n MulOp} {n Factor}}}}                                    mode value}
    }
    start {n Expression}
}

See how every single mode is value? That's the grammar living its truth, and the canonical form keeping all those keys in nice tidy dictionary order for us. Obsessed. 🫶

✨ PE SERIALIZATION FORMAT ✨

Okay bestie, gather round 💖. This is where we spill the tea on the format that the Parser Tools use to serialize Parsing Expressions as immutable values for transport, comparison, etc. No cap.

We gotta distinguish between regular and canonical serializations. The way that a parsing expression can have more than one regular serialization, but only exactly one of them will be canonical. Periodt. 💅

🌸 Regular serialization 🌸

✨ Atomic Parsing Expressions ✨

The string epsilon is an atomic parsing expression. It matches the empty string. Literally nothing, and it slays. 💖
The string dot is an atomic parsing expression. It matches any character. It’s giving “anything goes”. 👑
The string alnum is an atomic parsing expression. It matches any Unicode alphabet or digit character. This is a custom extension of PEs based on Tcl's builtin command string is. Lowkey iconic. ✨
The string alpha is an atomic parsing expression. It matches any Unicode alphabet character. This is a custom extension of PEs based on Tcl's builtin command string is. 🌸
The string ascii is an atomic parsing expression. It matches any Unicode character below U0080. This is a custom extension of PEs based on Tcl's builtin command string is. 🦋
The string control is an atomic parsing expression. It matches any Unicode control character. This is a custom extension of PEs based on Tcl's builtin command string is. 🎀
The string digit is an atomic parsing expression. It matches any Unicode digit character. Note that this includes characters outside of the [0..9] range. This is a custom extension of PEs based on Tcl's builtin command string is. 🔢
The string graph is an atomic parsing expression. It matches any Unicode printing character, except for space. This is a custom extension of PEs based on Tcl's builtin command string is. 📈
The string lower is an atomic parsing expression. It matches any Unicode lower-case alphabet character. This is a custom extension of PEs based on Tcl's builtin command string is. 🍓
The string print is an atomic parsing expression. It matches any Unicode printing character, including space. This is a custom extension of PEs based on Tcl's builtin command string is. 🖨️
The string punct is an atomic parsing expression. It matches any Unicode punctuation character. This is a custom extension of PEs based on Tcl's builtin command string is. ❗
The string space is an atomic parsing expression. It matches any Unicode space character. This is a custom extension of PEs based on Tcl's builtin command string is. 🌌
The string upper is an atomic parsing expression. It matches any Unicode upper-case alphabet character. This is a custom extension of PEs based on Tcl's builtin command string is. 🔠
The string wordchar is an atomic parsing expression. It matches any Unicode word character. This is any alphanumeric character (see alnum), and any connector punctuation characters (e.g. underscore). This is a custom extension of PEs based on Tcl's builtin command string is. 🔗
The string xdigit is an atomic parsing expression. It matches any hexadecimal digit character. This is a custom extension of PEs based on Tcl's builtin command string is. 🔡
The string ddigit is an atomic parsing expression. It matches any decimal digit character. This is a custom extension of PEs based on Tcl's builtin command regexp. 🔟
The expression [list t x] is an atomic parsing expression. It matches the terminal string x. 💬
The expression [list n A] is an atomic parsing expression. It matches the nonterminal A. 🏷️

🔥 Combined Parsing Expressions 🔥

For parsing expressions e1, e2, ... the result of [list / e1 e2 ... ] is a parsing expression as well. This is the ordered choice, aka prioritized choice. 💅
For parsing expressions e1, e2, ... the result of [list x e1 e2 ... ] is a parsing expression as well. This is the sequence. ✨
For a parsing expression e the result of [list * e] is a parsing expression as well. This is the kleene closure, describing zero or more repetitions. 🔁
For a parsing expression e the result of [list + e] is a parsing expression as well. This is the positive kleene closure, describing one or more repetitions. ➕
For a parsing expression e the result of [list & e] is a parsing expression as well. This is the and lookahead predicate. 👀
For a parsing expression e the result of [list ! e] is a parsing expression as well. This is the not lookahead predicate. 🙅
For a parsing expression e the result of [list ? e] is a parsing expression as well. This is the optional input. ❓

💎 Canonical serialization 💎

The canonical serialization of a parsing expression has the format as specified in the previous item, and then additionally satisfies the constraints below, which make it unique among all the possible serializations of this parsing expression. So extra, but make it make sense. 💎

The string representation of the value is the canonical representation of a pure Tcl list. I.e. it does not contain superfluous whitespace. 🧼
Terminals are not encoded as ranges (where start and end of the range are identical). 🚫

🦋 EXAMPLE 🦋

Assuming the parsing expression shown on the right-hand side of the rule

Expression <- Term (AddOp Term)*

then its canonical serialization (except for whitespace) is

{x {n Term} {* {x {n AddOp} {n Term}}}}

💀 BUGS, IDEAS, FEEDBACK 💀

This document, and the package it describes, will undoubtedly contain bugs and other problems. Not me being shocked. 😭 Please report such in the category pt of the Tcllib Trackers [http://core.tcl.tk/tcllib/reportlist]. Please also report any ideas for enhancements you may have for either package and/or documentation. We love a glow-up. 🫶

When proposing code changes, please provide unified diffs, i.e the output of diff -u. That’s the vibe. 📝

Note further that attachments are strongly preferred over inlined patches. Attachments can be made by going to the Edit form of the ticket immediately after its creation, and then using the left-most button in the secondary navigation bar. Iykyk. 💅

🔑 KEYWORDS 🔑

CONTAINER, EBNF, LL(k), PEG, TDPL, context-free languages, conversion, expression, format conversion, grammar, matching, parser, parsing expression, parsing expression grammar, push down automaton, recursive descent, serialization, state, top-down parsing languages, transducer

📦 CATEGORY 📦

Parsing and Grammars

© COPYRIGHT ©

Okay bestie, that’s the whole vibe. This page comes from tcllib version 1.1, and it’s the manual for pt::peg::to::container(n). Stay iconic! 💖✨

📦 where this page comes from

fedora 43: tcllib 2.0-3.fc43 · TCL
fedora 44: tcllib 2.0-4.fc44 · TCL
nixos 26.05: tcllib 2.0
nixpkgs unstable: tcllib 2.0
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash on 2026-10-18: a language model's rewrite of the original, under its terms

pt::peg::to::container(n)

💖 pt::peg::to::container — the pt::peg::to::container(n) page 💖

✨ NAME ✨

🌸 SYNOPSIS 🌸

🎀 DESCRIPTION 🎀

⭐ API ⭐

💅 OPTIONS 💅

🌈 GRAMMAR CONTAINER 🌈

💖 EXAMPLE 💖

🦋 PEG SERIALIZATION FORMAT 🦋

🌸 regular serialization 🌸

👑 canonical serialization 👑

💖 EXAMPLE 💖

✨ PE SERIALIZATION FORMAT ✨

🌸 Regular serialization 🌸

✨ Atomic Parsing Expressions ✨

🔥 Combined Parsing Expressions 🔥

💎 Canonical serialization 💎

🦋 EXAMPLE 🦋

💀 BUGS, IDEAS, FEEDBACK 💀

🔑 KEYWORDS 🔑

📦 CATEGORY 📦

© COPYRIGHT ©

💖 pt::peg::to::container — the `pt::peg::to::container(n)` page 💖